Optical lenses made of a transparent resin are lightweight, unlikely to be broken, and readily molded, compared with optical lenses composed of inorganic glass. When the transparent resin is a transparent polyamide resin,ri gidity and heat resistance during reflow soldering can be imparted by crosslinking. Therefore, optical lenses composed of a transparent polyamide resin which has been crosslinked by electron beam irradiation or the like are widely used for various optical instruments.
For example, Patent Literature 1 discloses an optical lens, which includes a molded body composed of a molding material (resin composition) containing a transparent polyamide and a stabilizer, which is obtained by crosslinking the transparent polyamide by irradiation, which has a total light transmission of 60% or more when the molded body has a thickness of 2 mm, and which has satisfactory rigidity in the range of room temperature to a high temperature and high heat resistance during reflow soldering, in which the problem of thermal deformation is unlikely to occur even when the temperature of the usage environment increases.
Patent Literature 2 discloses a transparent polyamide resin molded body which is composed of a resin composition containing a transparent polyamide resin, a crosslinking auxiliary, and an antioxidant, which is obtained by crosslinking the transparent polyamide resin, and which has a storage elastic modulus of 10 MPa or more at 270° C., and an optical lens including the resin molded body.